The acute abdomen following cardiopulmonary bypass surgery

Over a 5-year period, 9 patients (0.85 per cent) developed a major acute abdominal complication after cardiopulmonary bypass surgery. Difficulties in the initial recognition and diagnosis of these complications in sedated, ill patients are highlighted. A high index of suspicion is important in the early diagnosis of these complications. The numbers are too small for statistical analysis, but experience suggests that each case should be dealt with on its merits in accordance with common surgical practice and that operative management should not be rejected because the patient has recently undergone a major cardiac operation.     

Continuous haemodiafiltration during and after cardiopulmonary bypass in renal failure patients

Present investigation was undertaken to study the effects of 6 week treatment with spirapril (2 mg/kg po) on insulin sensitivity, and serum lipid levels in streptozotocin (STZ)-diabetic and spontaneously hypertensive (SH) rats. Treatment of rats with spirapril in diabetic and diabetic with hypertensive animals significantly prevented STZ-induced loss of body weight, hypertension, and bradycardia. It also partially but significantly prevented STZ-induced hyperglycaemia in both diabetic Wistar and SH animals. Insulin level was not altered by spirapril treatment. There was significant reduction in cholesterol levels in the diabetic rats. In conclusion, the present investigation presents a number of beneficial effects of spirapril treatment in diabetic and/or hypertensive rats. Spirapril may be considered as one of the drugs of choice in treatment of hypertension when associated with diabetes     

Independent association between acute renal failure and mortality following cardiac surgery

With the increasing frequency of surgical operations to the cavernous sinus greater knowledge of the microanatomy of the cavernous sinus has become necessary. The most frequently seen complications during cavernous sinus surgery involve impairment of cranial nerves. This can occur due to direct damage or ischemia. For these reasons, it is important to know the arterial supplies to the cranial nerves in the cavernous sinus and the anatomy of these branches as well. 15 formaline fixed adult cadavers were used in this study. Before the dissections, the internal carotid artery and vertebral artery were filled with coloured latex on both sides. In this report, the intracavernous branches of internal carotid artery (I.I.C.A.) were identified based on the principles of Nomina Anatomica (1989) and compared with others. In our study we found that the segment of the abducens nerve which lies in Dorello's channel was supplied by the meningeal branch; from the point at which it pierces the cerebellar tentorium, the trochlear nerve is supplied by the tentorial cerebellar artery; the posterior cerebellar artery supplies the proximal segment of the oculomotor nerve that proceeds to the oculomotor triangle. Except for these, all the cranial nerves that were located on the lateral wall of the sinus cavernosus are supplied by the tentorial marginal branch and the branches of the lateral trunk.     

Measurement of cerebral blood flow during cardiopulmonary bypass with near-infrared spectroscopy

OBJECTIVES: We sought to assess the incidence and clinical relevance of examination data to recurrent ischemia within an international randomized trial. BACKGROUND: Ischemic symptoms commonly recur after thrombolysis for acute myocardial infarction. METHODS: Patients (n = 40,848) were prospectively evaluated for recurrent angina and transient electrocardiographic (ECG) or hemodynamic changes. Five groups were developed: Group 1, patients with no signs or symptoms of recurrent ischemia; Group 2, patients with angina only; Group 3, patients with angina and ST segment changes; Group 4, patients with angina and hemodynamic abnormalities; and Group 5, patients with angina, ST segment changes and hemodynamic abnormalities. Baseline clinical and outcome variables were compared among the five groups. RESULTS: Group 1 comprised 32,717 patients, and Groups 2 to 5 comprised 20% of patients (4,488 in Group 2; 3,021 in Group 3; 337 in Group 4; and 285 in Group 5). Patients with recurrent ischemia were more often female, had more cardiovascular risk factors and less often received intravenous heparin. Significantly more extensive and more severe coronary disease, antianginal treatment, angioplasty and coronary bypass surgery were observed as a function of ischemic severity. The 30-day reinfarction rate was 1.6% in Group 1, 6.5% in Group 2, 21.7% in Group 3, 13.1% in Group 4 and 36.5% in Group 5 (p < 0.0001); in contrast, the 30-day mortality rate was significantly lower (p < 0.0001) in Groups 1, 2 and 3 (6.6%, 5.4% and 7.7%, respectively) than in Groups 4 and 5 (21.8% and 29.1%). CONCLUSIONS: Postinfarction angina greatly increases the risk of reinfarction, especially when accompanied by transient ECG changes. However, mortality is markedly increased only in the presence of concomitant hemodynamic abnormalities.     

Renal transplantation following renal failure due to urological disorders

BACKGROUND: Renal allograft outcome, during an 8 year period (1985-1992), has been assessed in 56 renal transplants performed in 55 patients who had end-stage renal failure as a consequence of urological abnormalities. The abnormalities were: primary vesicoureteric reflux (VUR) or renal dysplasia (26 patients); posterior urethral valves (PUV) (15); neuropathic bladders (6); vesico-ureteric tuberculosis (5); bladder exstrophy (3); and prune belly syndrome (1). Six patients had augmented bladders, and eight transplants were performed in seven patients with urinary diversions. RESULTS: Overall, 1 and 5 year actuarial graft survival was 89 and 66%, with mean creatinine of 154 micromol/l +/- 11 (SE) and 145 +/- 9 respectively. Patients with abnormal bladders or conduits (n = 28) had worse graft function than those with normal bladders (n = 28) although graft survival was not significantly different in the two groups at 1 and 5 years: 93 and 75% with normal bladders vs 86 and 57% with abnormal systems. Symptomatic urinary tract infections were common in the first 3 months after transplantation (63%); fever and systemic symptoms occurred in 39% with normal bladders and 59% with abnormal bladders. Urinary tract infection directly contributed to graft loss in six patients with abnormal bladders, but had no consequences in those with normal bladders. CONCLUSIONS: Abnormal bladders must be assessed urodynamically before transplantation, and after transplantation adequacy of urinary drainage must be re-assessed frequently. Prophylactic antibiotics are now given for the first 6 months and urinary tract infections must be treated promptly. With these measures, good results, similar to those of patients without urological problems, can be obtained.     

Alterations in renal microcirculation during cardiopulmonary bypass

BACKGROUND: This study was designed to investigate renal microvascular changes during cardiopulmonary bypass. METHODS: Kidneys were harvested from each of four groups of 6 pigs. Group A were anesthetized and heparinized only. The remaining three groups underwent cardiopulmonary bypass at 28 degrees C, group B for 30 minutes and groups C and D for 120 minutes; group D had an additional 30 minutes of normothermic perfusion at the end of the experiment. Renal cortical blood flow was measured using radiolabeled microspheres. Microvascular morphology was defined by corrosion casting and scanning electron microscopy. RESULTS: In group A, renal vascular resistance was 61+/-5.1 mm Hg x mL(-1) x min(-1). This value decreased to 28+/-7.8 in group B and 25+/-4.0 in group C (p < 0.05), and increased in group D to 40+/-4.1 (p < 0.05 versus groups A, B, and C). Cortical thickness, as measured by microvascular casts in groups A, B, and C, was 33, 34, and 31 mm, respectively, with equal distribution of the resin to the superficial and deep cortex but was significantly reduced in group D to 22 mm (p < 0.05 versus groups A, B, and C), with failure of the resin to fill the superficial cortical layer. Diameters of glomeruli as seen on the casts were 111+/-10.38 microm in group A, 100+/-9.24 microm in group B, and 82+/-4.4 microm in group C (p < 0.05 group A versus group C). The glomeruli from group D were still significantly smaller than group A (93+/-10.35 microm, p < 0.05). Mean glomerular capillary diameters were 4.65+/-0.26 microm in group A, 3.9+/-0.16 microm in group B, 3.6+/-0.19 microm in group C, and 3.65+/-0.3 microm in group D (p < 0.05 group A versus groups B, C, and D). CONCLUSIONS: Hypothermic nonpulsatile cardiopulmonary bypass decreased renal vascular resistance, but the superficial and deep layers of the cortex were perfused equally. Glomeruli were reduced in size because of capillary narrowing. This was consistent with diversion of blood through bypass channels. With restoration of normothermia, underperfusion of the superficial cortex occurred, with potential for damage to these nephrons during the increased metabolic demands of rewarming.     

Epinephrine-induced lactic acidosis following cardiopulmonary bypass

OBJECTIVE: To determine if lactic acidosis occurring after cardiopulmonary bypass could be attributed to the metabolic or other effects of epinephrine administration. DESIGN: Prospective, randomized study. SETTING: Postsurgical cardiothoracic intensive therapy unit. PATIENTS: Thirty-six adult patients, without acidosis, requiring vasoconstrictors for the management of hypotension after cardiopulmonary bypass. INTERVENTIONS: Randomized administration of either epinephrine or norepinephrine by infusion. MEASUREMENTS AND MAIN RESULTS: Hemodynamic and metabolic data were collected before commencement of vasoconstrictor therapy (time 0) and then 1 hr (time 1), 6 to 10 hrs (time 2), and 22 to 30 hrs (time 3) later. Six of the 19 patients who received epinephrine developed lactic acidosis. None of the 17 patients receiving norepinephrine developed lactic acidosis. In the epinephrine group, but not in the norepinephrine group, lactate concentration increased significantly at times 1 and 2 (p = .01), while pH and base excess decreased (p < or = .01). Blood glucose concentration was higher in the epinephrine group at time 2 (p = .02), while the cardiac index (p < .03) and the mixed venous Po2 (p = .04) were higher at time 1. compared with the norepinephrine group, the patients receiving epinephrine had higher femoral venous lactate concentrations (p = .03), increased lower limb blood flow (p = .05), and increased femoral venous oxygen saturations (p = .04). CONCLUSIONS: The use of epinephrine after cardiopulmonary bypass precipitates the development of lactic acidosis in some patients. This phenomenon is presumably a beta-mediated effect, and is associated with an increase in whole-body and lower limb blood flow and a decrease in whole-body and transfemoral oxygen extraction. The phenomenon does not appear to be related to reduced tissue perfusion and does not have the poor outlook of lactic acidosis associated with shock.     

Unusual dyskinesia complicating cardiopulmonary bypass surgery

Four infants developed dyskinesia after cardiopulmonary bypass surgery three to four days postoperatively. The dyskinesia was choreoathetotic, and involved mainly the mouth, tongue and face. It was absent during sleep. Three of these infants improved over periods of several weeks, but one infant remained dyskinetic one year postoperatively. Neuro-imaging studies and EEGs were of little value in determining the cause of the dyskinesia. The factors responsible for the involuntary movements and for their severity remain unexplained.     

Autologous blood transfusion during cardiopulmonary bypass

Immediately prior to cardiopulmonary bypass, two units of blood were removed from each of 25 patients undergoing open-heart surgery, and the autologous blood was reinfused after cessation of support with the pump oxygenator. Pertinent data on blood balance and hematologic measurements were compared to a matched group of control subjects. There were no significant differences in the amount of operative or postoperative bleeding, the requirements for homologous blood and blood products, or the amount of protamine needed for neutralization of heparin.     

Free-water clearance and the early recognition of acute renal insufficiency after cardiopulmonary bypass

The predictive value of free-water clearance measurements for the early recognition of acute renal insufficiency was evaluated in 59 patients immediately following cardiopulmonary bypass. Blood urea nitrogen and serum creatinine measurements were taken before and after operation. Intraoperatively, immediately after completion of bypass, urine and serum samples were obtained for osmolality. Duration of bypass, urine output, degree of hemolysis, and quality of perfusion were recorded. Fifty-four patients developed no signs of renal insufficiency following bypass, and all had free-water clearance values equal to or less than -20 ml per hour. Five patients who had free-water clearance values equal to greater than -8 ml per hour developed manifestations of an acute renal insufficiency state. There were no false-negative or false-positive determinations. Consequently, free-water clearance measurements appear to be a reliable indicator of those patients who will develop renal insufficiency following cardiopulmonary bypass. Early recognition provides an opportunity immediately after operation for initiating treatment consisting of administration of diuretics, potassium restriction, and oliguric fluid regimens.     

The relation between arterial oxygen tension and cerebral blood flow during cardiopulmonary bypass

BACKGROUND: The precise mechanisms involved in islet xenograft rejection remain unknown. The purpose of the present study was to determine cellular mechanisms responsible for islet xenograft rejection in the liver to facilitate finding a procedure for prevention of immune rejection. METHODS: Hepatic mononuclear cells (MNC) as well as splenocytes, peripheral blood MNC, and thymocytes from streptozotocin-induced diabetic mice (BALB/c) rejecting the intrahepatic rat (Lewis) islet xenografts were isolated and examined by two-color FACS analysis. RESULTS: The characteristic finding of the hepatic MNC from the mice rejecting islet xenografts compared with mice receiving isografts was a significant increase in the yield as well as in the percentage of the cells expressing CD3+ interleukin-2 receptor (IL-2R) alpha- beta+, CD3+ CD8alpha+ beta+, and T cell receptor (TCR) alphabeta+ lymphocyte function-associated antigen-1+. The expression of CD3 and TCR alphabeta of these T cells was found to be of intermediate intensity (TCR(int) cells). The expansion of these TCR(int) cells occurred predominantly in the liver. There was no significant difference in the cells expressing CD3+ IL-2R alpha+, CD3+ CD4+, CD3+ TCRgammadelta+, CD3- IL-2Rbeta+ (natural killer cells), and B220+ (B cells). In vivo administration of anti-IL-2Rbeta monoclonal antibody directed to the expanded cells produced a prevention of rejection. CONCLUSIONS: These findings suggest that islet xenograft rejection in the liver from rat to mouse is an event for which the TCR(int) cells are responsible.     

Regional blood flow during pulsatile cardiopulmonary bypass and after circulatory arrest in an infant model

BACKGROUND: Pulsatile perfusion systems have been proposed as a means of improving end-organ perfusion during and after cardiopulmonary bypass. Few attempts have been made to study this issue in an infant model. METHODS: Neonatal piglets were subjected to nonpulsatile (n = 6) or pulsatile (n = 7) cardiopulmonary bypass and 60 minutes of circulatory arrest. Cerebral, renal, and myocardial blood flow measurements were obtained at baseline, on bypass before and after circulatory arrest, and after bypass. RESULTS: Cerebral blood flow did not differ between groups at any time and was diminished equally in both groups after circulatory arrest. Renal blood flow was diminished in both groups during bypass but was significantly better in the pulsatile group than in the nonpulsatile group prior to, but not after, circulatory arrest. Myocardial blood flow was maintained at or above baseline in the pulsatile group throughout the study, but in the nonpulsatile group, it was significantly lower than baseline during CPB prior to circulatory arrest and lower compared with baseline and with the pulsatile group 60 minutes after CPB. CONCLUSIONS: Pulsatile bypass does not improve recovery of cerebral blood flow after circulatory arrest, may improve renal perfusion during bypass but does not improve its recovery after ischemia, and may have beneficial effects on myocardial blood flow during bypass and after ischemia compared with nonpulsatile bypass in this infant model.     

Pulsatile versus nonpulsatile flow. No difference in cerebral blood flow or metabolism during normothermic cardiopulmonary bypass in rabbits

BACKGROUND: Although pulsatile and nonpulsatile cardiopulmonary bypass (CPB) do not differentially affect cerebral blood flow (CBF) or metabolism during hypothermia, studies suggest pulsatile CPB may result in greater CBF than nonpulsatile CPB under normothermic conditions. Consequently, nonpulsatile flow may contribute to poorer neurologic outcome observed in some studies of normothermic CPB. This study compared CBF and cerebral metabolic rate for oxygen (CMRO2) between pulsatile and nonpulsatile CPB at 37 degrees C. METHODS: In experiment A, 16 anesthetized New Zealand white rabbits were randomized to one of two pulsatile CPB groups based on pump systolic ejection period (100 and 140 ms, respectively). Each animal was perfused at 37 degrees C for 30 min at each of two pulse rates (150 and 250 pulse/min, respectively). This scheme created four different arterial pressure waveforms. At the end of each perfusion period, arterial pressure waveform, arterial and cerebral venous oxygen content, CBF (microspheres), and CMRO2 (Fick) were measured. In experiment B, 22 rabbits were randomized to pulsatile (100-ms ejection period, 250 pulse/min) or nonpulsatile CPB at 37 degrees C. At 30 and 60 min of CPB, physiologic measurements were made as before. RESULTS: In experiment A, CBF and CMRO2 were independent of ejection period and pulse rate. Thus, all four waveforms were physiologically equivalent. In experiment B, CBF did not differ between pulsatile and nonpulsatile CPB (72 +/- 6 vs. 77 +/- 9 ml.100 g-1.min-1, respectively (median +/- quartile deviation)). CMRO2 did not differ between pulsatile and nonpulsatile CPB (4.7 +/- 0.5 vs. 4.1 +/- 0.6 ml O2.100 g-1.min-1, respectively) and decreased slightly (0.4 +/- 0.4 ml O2.100 g-1.min-1) between measurements. CONCLUSIONS: During CPB in rabbits at 37 degrees C, neither CBF nor CMRO2 is affected by arterial pulsation. The absence of pulsation per se is not responsible for the small decreases in CMRO2 observed during CPB.     

Management of postoperative heparin rebound following cardiopulmonary bypass

Postoperative heparin rebound was investigated in 50 adult patients undergoing cardiopulmonary bypass with the use of the Hepcon heparin analyzer. Prior to bypass each patient received 2 mg/kg of heparin. During bypass, the activated clotting time (ACT) was utilized to assess the need for additional heparin to maintain the value between 300 and 400 seconds. The average amount of heparin given was 160 mg. Once cardiopulmonary bypass was terminated the Hepcon unit was employed to determine the actual amount of active circulating heparin and to calculate the dose of protamine sulfate. The average amount of protamine administered intraoperatively was 200 mg. The overall mean ratio of protamine-to-heparin was 1.25 : 1. Once hemostasis was achieved, no circulating heparin was measured with the Hepcon unit, and the ACT value had returned to its baseline, the incisions were closed and the patients were transferred to the intensive care unit. One hour later a blood sample was obtained and analyzed by the Hepcon unit for any heparin rebound. We found that 26 patients (52%) had circulating heparin and required an additional dose of protamine, averaging 70 mg. Drainage from the thoracotomy tubes averaged 400 cc in the first 24 hours, and a mean of 2 units of packed cells was infused. Three patients (6%) did not require any blood transfusions. The use of the Hepcon unit has produced a safe and expedient method of analyzing and neutralizing active circulating heparin in patients following cardiopulmonary bypass. It is a useful adjunct in blood conservation because it reduces excessive postoperative blood loss associated with heparin rebound.     

The acute phase response to cardiopulmonary bypass in children

We recently obtained the brain of a rare lemuroid primate, Cheirogaleus medius. The brain was not perfused before death, but rather fixed by immersion shortly thereafter. In both flat-mounted and transversely sectioned tissue, we were able to clearly demonstrate periodic zones of high cytochrome oxidase (CO) activity in the primary visual cortex, resembling the so-called 'blobs' described in many other primate species. Our results contrast with a previous report indicating that blobs are absent in Cheirogaleus medius and provide support for the view that blobs are an evolutionary specialization of primate visual cortex that evolved only once, early in primate history. In other aspects of architectonic organization, area V1 of this Cheirogaleus individual closely resembles that of other strepsirhine primates, such as Galago. We were able to identify additional divisions of cortex in this individual, including the middle temporal visual area (MT), auditory cortex, and the primary somatosensory area (S1 or area 3b). These observations indicate that valuable neuroanatomical information can, in favorable cases, be obtained from rare mammalian species that die of natural causes in captivity or which must be euthanized, even though the animals have not been perfused.